Effectiveness of cultural thatch-mat controls for young and mature Kikuyu turfgrass
Excessive thatch and mat can be detrimental to turfgrass health and management. Mechanical and topdressing techniques to reduce accumulation of thatch and mat were evaluated in a 24-mo field study of kikuyu [Pennisetum clandestinum (Hochst. ex Chiov.)] turfgrass of two contrasting organic matter (OM) contents in the surface 50 mm of soil. Treatments included two kikuyugrass ages (established from 20 wk or 20-yr-old kikuyugrass) and five renovation techniques (none, verticutting, coring, topdressing with sand, coring + topdressing). The renovation techniques varied in effectiveness depending on the initial OM content of the soil immediately underlying the kikuyugrass. Annual verticutting, or twice annual topdressing with or without annual coring a young kikuyugrass were most successful at restricting the accumulation of soil OM (P < 0.05), with OM content <3.5% by 24 mo. Twice annual topdressing with or without annual coring, most rapidly decreased soil OM in the mature kikuyugrass (P < 0.05), with OM content averaging 6.2% by 24 mo. Combining coring with topdressing did not necessarily further decrease OM contents. Topdressing was up to three times more effective at reducing soil OM content than coring alone (P < 0.05). The color and N concentration of both kikuyugrass ages was maintained to local standards by all mechanical and topdressing techniques, although verticutting decreased the incidence of mower scalping in the second year. Verticutting was the most effective approach for restricting the progressive softening of young kikuyugrass with time (P < 0.05), whereas the mature kikuyugrass softened by the same amount irrespective of the renovation treatment.